Footwear sole and method of manufacture and related aspects

ABSTRACT

A footwear sole comprises an first sole portion including at least one protruding male engagement part and a second sole portion including at least one recessed female engagement part having a shape which closely conforms to that of a corresponding male portion, whereby when a force is applied to the first sole portion in the direction of the second sole portion, the corresponding male engagement part is fixedly retained by the female engagement part. In this manner a shoe-sock may be fixed to the second or another portion of the sole without the need for any adhesive to be used.

FIELD OF THE INVENTION

The disclosed technology relates to a sole for an item of footwear and a method of manufacture of the same and related aspects, particularly but not exclusively, to a sole which enables footwear to be manufactured without requiring adhesive materials to be used to fix at least an upper fabric portion of the footwear item to a sole portion during manufacture of the footwear item.

BACKGROUND

Footwear, especially trainers and the like, are often manufactured using materials which are non-environmentally friendly. Whilst so-called “vegan shoes” and the like are well-known, they are usually constructed using techniques which make large-scale production challenging and/or have design comprises due to the manufacturing challenges

The embodiments described below are provided by way of example only.

SUMMARY

Some examples of the embodiments of the disclosed technology seek to provide a footwear sole which allows for adhesive free fixation of a shoe-upper or shoe-sock to sole components such as a mid-sole of an item of footwear.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

A footwear sole comprises at least a first, or inner, sole portion which includes at least one protruding engagement part (also referred to herein as a male engaging part, element or portion). In one embodiment, at least three engagement parts are provided, for example, with one engagement part located in a heel region of the sole, a second engagement part located in a mid-foot region of the sole, and a third engagement part located in the fore-foot region of the sole. In one embodiment, the engagement parts extend from the underside of the inner sole to engage with a second sole portion of the footwear, in other embodiments a mixture of male and female engagement elements may be formed on each of the first and/or second sole portions. The second sole portion may comprise, for example, a mid-sole (or in some embodiments, an outer sole) includes at least one recessed engagement part (also referred to herein as a female engagement part and/or a reciprocating engagement part) which has a shape which closely conforms to that of the corresponding protruding engagement part. When a force is applied to drive the first sole portion against the second sole portion, each protruding engagement part is forced into engagement with a corresponding and reciprocating recessed engagement part. By locating the first sole portion within a shoe upper or shoe sock, such that the so-called male engagement parts protrude through the shoe-sock material, for example, through one or more apertures in the base or foot of the shoe-sock, the shoe-sock is fixed in place, enabling it to be secured to other parts of the footwear such as another sole portion, which may be the first sole portion or the second sole portion or another, for example, outer portion of the sole without the need for any adhesive to be used. This enables what is usually referred to “glue-less” footwear or shoes to be made which are both aesthetically appealing and which are capable of being mass produced in a factory environment. The terms “male” engagement part and “female” engagement part refer herein to the manner in which such fixation elements engage or couple with each other, for example, a “bolt” may be considered to form a male engagement part which engages with a reciprocating female engagement part in the form of a “nut”.

Some examples of embodiments of the disclosed technology relate to a footwear sole comprising:

-   -   a first sole portion including at least one protruding male         engagement part;     -   a second sole portion including at least one recessed female         engagement part having a shape which closely conforms to that of         a corresponding male portion, whereby when a force is applied to         the first sole portion in the direction of the second sole         portion, the corresponding male engagement part is fixedly         retained by the female engagement part

In at least one example embodiment of a footwear sole the first sole portion may comprise an inner sole positioned within a shoe-sock and the at least one corresponding protruding male engagement part passes through an aperture in said shoe-sock to engage with said recessed female engagement part.

In at least one example embodiment of a footwear sole the footwear sole may be used in the construction of an item of footwear and retains the position of the shoe-sock relative to the second sole portion whilst the shoe-sock is fixed to the second sole portion using non-adhesive based retaining technique.

In at least one example embodiment of a footwear sole, the non-adhesive base retaining technique may comprise stitching the shoe-sock to the second sole portion.

In at least one example embodiment of a footwear sole, the second sole portion may comprise a mid-sole of an item of footwear.

In at least one example embodiment of the disclosed technology, the footwear sole further comprises:

-   -   at least one additional engagement part located in at least one         of said at least one protruding male engagement part; and         at least one reciprocating additional engagement part located in         at least one of said at least one recessed female engagement         part.

In at least one example embodiment of a footwear sole, at least one of the at least one additional engagement parts may protrude from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.

In at least one example embodiment of a footwear sole, at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.

In at least one example embodiment of the footwear sole the protruding additional engagement part forms a protrusion which comprises an additional component part that passes through at least part of the protruding male engagement part.

In at least one example embodiment of a footwear sole, the at least one protruding additional element comprises one or more of the following:

-   -   a dowel and the reciprocal element comprises a recess;     -   a screw and the reciprocal element comprises a recess;     -   a bolt and the reciprocal element comprises a nut in a recess;     -   a male part of a snap-fastener type mechanism and the reciprocal         element comprises a female part of a snap-fastener mechanism.

Some examples of embodiments of the disclosed technology relate to a method of constructing an item of footwear, the method comprising: forming a first sole portion having at least one protruding male engagement part; forming a second sole portion having at least one recessed female engagement part; positioning the first sole portion within a shoe-sock, such that said at least one protruding male engagement part extends through the foot-base of the shoe-sock; positioning a second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part; and forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position.

In at least one example embodiment of the method, the shoe-sock is further secured to at least one of the second sole using an adhesive free technique.

In at least one example embodiment of the method, wherein the adhesive free technique comprises stitching.

In at least one example embodiment of the method, the second sole portion comprises a mid-sole of an item of footwear, and the method further comprises covering at least part of the mid-sole with an outer sole.

In at least one example embodiment of the method, the method further comprises: forming at least one additional engagement part in at least one of said at least one protruding male engagement part; forming at least one corresponding reciprocating additional engagement part in at least one of said at least one recessed female engagement part, wherein the positioning of the second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part aligns the additional engagement part with the reciprocating female engagement part.

In at least one example embodiment of the method, forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position further causes the additional engagement part and the reciprocating additional engagement part to similarly engage with each other.

In at least one example embodiment of the method, forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts are affixed to each other and retain the shoe sock in position using a first mechanism for engagement further causes the additional engagement part and the reciprocating additional engagement part to be suitably located for engaging using a different mechanism of engagement.

In at least one example embodiment of the method, at least one of the at least one additional engagement parts protrudes from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.

In at least one example embodiment of the method, at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.

In at least one example embodiment of the method, the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess or cam-type locking mechanism in a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.

Many other examples of main and secondary engagement mechanisms may be adopted in various embodiments of the invention, as would be apparent to one of ordinary skill in the art, where the secondary engagement mechanism is disposed within the main engagement mechanism, such as in a snap-fastening type of mechanism.

In at least one example embodiment of the method, the force applied to the first sole portion or second sole portion to cause the engagement of the first and a second sole portions is directed in a substantially perpendicular direction inwards towards the surface of one or other or both of the first (inner) sole and second (mid-sole) sole portions.

The inner sole may be formed integrally with at least one engagement member and/or the mid-sole may also formed integrally with at least one engagement member, for example, either by machine-tooling a blank or by casting a mold for one or both of the inner sole and/or mid-sole.

Whilst some examples of embodiments of the disclosed technology refer to the inner sole having as a primary engagement mechanism a protruding or male engagement portion, and the mid-sole (which in some embodiments may comprise an outer sole), comprises the reciprocal recessed or female engagement portion, in other examples of embodiments of the disclosed technology at least one engagement portion is configured as a female engagement portion in the inner-sole and the protruding male engagement portion is formed in the a sole portion.

The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:

FIG. 1 shows a schematic diagram of an item of footwear according to some examples of embodiments of the disclosed technology;

FIG. 2A shows a schematic side view of the lower portion of an item of footwear according to some embodiments of the disclosed technology.

FIG. 2B shows a schematic cross-sectional view of the lower portion of the item of footwear shown in FIG. 2A according to some embodiments of the disclosed technology.

FIG. 3A is a black-and-white photograph providing a view of the medial side of an item of footwear according to an example of an embodiment of the disclosed technology which indicates some internal features of the item of footwear.

FIG. 3B is a black-and-white photograph providing a side view of the medial side of an item of footwear according to an example of an embodiment of the disclosed technology which indicates some internal features of the item of footwear.

FIG. 3C is a black-and-white photograph providing a view of the base of the outer sole of an item of footwear according to an example of an embodiment of the disclosed technology which indicates some internal features of the item of footwear.

FIG. 3D is a black-and-white photograph providing a rear-side view of the heel region of an item of footwear according to an example of an embodiment of the disclosed technology which indicates some internal features of the item of footwear.

FIGS. 4A to 4C are a black-and-white photographs enlarging the forefoot, mid-foot, and heel regions of the image shown in FIG. 3B.

FIGS. 5A to 5D are black and white photographs showing a different views of a model of a base of an item of footwear according to an example of an embodiment of the disclosed technology.

FIGS. 6A to 6D are schematic cross-section views of different examples of engagement mechanisms for the inner and outer sole portions according to some embodiments of the disclosed technology.

Common reference numerals are used throughout the figures to indicate similar features.

DETAILED DESCRIPTION

Embodiments of the disclosed technology are described below by way of example only. These examples may represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

FIG. 1 shows a schematic diagram of a side view of the exterior of an item of footwear 10 according to some examples of embodiments of the disclosed technology. The term item of footwear as used herein may refer to a shoe, boot, trainer or the like, which comprises an upper portion 12 covering an retaining a foot in contact with a lower portion 14 which supports the sole of a foot when it is within the item footwear. Upper portion 12 accordingly provides a “body” for the item of footwear comprising a shoe “sock” 16 which extends over the heal region 20 a, mid-foot region 20 b, and forefoot (or toe) region 20 c.

The item of footwear 10 is worn by inserting a foot is inserted via opening 18 located around the heal end 20 a of the shoe sock 16. At least a portion of the shoe sock 16 may be constructed using elastomeric materials or the like in some embodiments so that the shoe sock 16 can be deformed to allow a foot to be inserted via opening 18 and then retract to retain the foot securely within the cavity portion of the shoe sock 16. Alternatively one or more of a number of releasable fastening mechanisms are well known which may be used to secure a foot within the shoe sock 16 (for example, by using a shoe-lace, strap and buckle, or Velcro type strap, zipper, press-stud or even a hook and eyelet).

Also visible from the exterior of the item of footwear 10 is outer sole portion 22 which in this example of an embodiment of a footwear item 10 includes a lateral or sidewall portion 24 which extends laterally around the side of the lower portion 14 of the item of footwear 10 and a base portion 26. Optionally, and as shown in FIG. 1, the outer sole portion 22 may further include a fixation portion 28, which may allow the upper portion 12 of the item of footwear 10 to be fixed to the outer sole portion 22, for example, by using a stitching technique.

Also visible from the exterior of the item of footwear 10 shown in FIG. 1 is a mid-sole portion 30 which also comprises a base portion 32 and an upper portion 34. Upper portion 34 forms a side-wall which extends around the shoe sock 16 and may further include a fixation section 26 which enables the shoe sock 16 to be fixed to the upper portion 34 of the mid-sole 30, for example, by stitching.

The upper part of FIG. 2A is a side view of a schematic of the exterior of the lower portion 14 of an embodiment of an item of footwear 10 according to some embodiments of the disclosed technology such as the example of an embodiment of an item of footwear 10 shown in FIG. 1 of the accompanying drawings. The lower part of FIG. 2A shows the alignment of the upper part showing lower portion 14 with the base 26 of the outer sole portion 22.

In FIG. 2B additional construction elements located within the item of footwear in the interior of the lower portion 14 are now visible comprising a first female engaging portion hereafter referred to as a “recess”, 40 a located in the heel portion 30 a of the midsole 30, a second recess 40 b located in the mid-foot portion 20 b of the mid-sole 30, and a third recess 40 c located in the fore-foot portion 20 c of the mid-sole 30. In some other embodiments of an item of footwear a different number of recesses may be provided in the mid-sole 30.

As shown in the schematic diagram of FIG. 2B, each recess 38 a,b,c, comprises sidewall portion(s) 40 a,b and a base portion 42. As shown, each recess 38 a,b,c, has a different depth dependent on the proportionate thickness of the mid-sole at the point where it is provided. The side-profile of the recesses 38 a,b,c, in the example of the embodiment shown in FIG. 2B shows that for each recess the sidewalls 40 a,b may make different angles with the base portions 42. Also, as shown for recess 38 a in FIG. 1, the rear-foot or heel side wall 40 a may make an obtuse angle 81 being slightly or substantially greater 90 degrees with the base 42 of the recess 38 a whereas the side-wall 40 b along the fore-foot side of the recess 38 may make an acute angle φ1 with the base of the recess 42. In some embodiments θ1 may be less than θ2 which may be less than θ3, and similarly φ1 may greater than φ2, may be greater than φ3, to accommodate the changing profile of the mid-sole (i.e. as the height of the mid-sole 30 generally decreases as one moves from the rear 20 a to the front or toe portion 20 c of the mid-sole 30).

Further examples of the shapes of the recesses 38 a,38 b, 38 c are shown herein below with reference to the other drawings, and it will be appreciated that the shape of the recesses shown in FIG. 2B are exemplary only, and a range of shapes from square, rectangular to parallelograms and rhomboids may be provided. There is a certain functional advantage to be obtained from some shapes, however, in terms of enabling better engagement or fixation with one or more male engagement parts 44 of an inner sole 46 (not shown in FIG. 2B), hereinafter referred to as engagement parts 44.

FIG. 3A is a black-and-white photograph providing a view of the medial side of an item of footwear 10 according to an example of an embodiment of the disclosed technology which indicates some further internal features of the item of footwear 10. As shown in the example in FIG. 3A, the item of footwear comprises an upper portion 12 comprising a shoe sock 16 in which the opening 18 is closed using shoe-laces. Also visible in FIG. 3A is the cut-way portion of the mid-sole 30, and also inner-sole engagement parts 44 a, 44 b of an inner sole 44. Inner sole 44 is retaining within the interior of the shoe sock 16 and is not visible in FIG. 3A, but in the heal region inner sole a protruding male engagement part 44 a and the mid-foot protruding male engagement part 44 b can be seen.

FIG. 3B is a black-and-white photograph providing a cut-away side view of the medial side of the lower portion 12 of the item of footwear shown in FIG. 3A. In FIG. 3B, internal features of the item of footwear 10. FIG. 3 shows inner sole 46 having three engagement parts 44 a,b,c, protruding through shoe sock 16. In the heel portion 30 a, the base of the inner sole 46 is visible through an aperture in the heal-portion 20 a of the shoe sock 16. Each protruding element 44 a,b,c, of the inner sole 46 conforms closely to the contour of a corresponding recess portion 38 a,b,c of the mid sole 30. As shown in FIG. 3B, the rear inner sole engagement part 44 a, has a base element 40 which rests upon the base 42 of the corresponding recess 38 a. The inner sole engagement part side wall(s) 48 form a rear angle 52 a and a fore angle 54 a with base element 50 and as can be seen in FIG. 3B, which conform to the fore angle φ1 and rear angle θ1 of the recess in the mid-sole.

As the cross-sectional view shows, the shape(s) of the inner sole engagement parts, for example, the contours and the angles of at least one of the side-walls 48 of each of the inner sole engagement parts 44 a,b,c make with the base of the engagement parts 50 a,b,c, are such that the engagement parts conform closely with the shape(s) of the corresponding sidewalls 40 and bases 42 a,b,c of the recesses 38 a,b,c, in the mid-sole 30. To engage the inner sole 46 with the mid-sole 30, force is applied in a suitable direction to cause the protruding engagement part 44 a,b,c to be inserted into the corresponding recesses 38 a,b,c.

Engagement may result, for example, from the shapes and/or relative sizes of the recess and/or engagement parts. For example, if the recess is suitable shaped so that a flange, lip or rim or the like is provided along at least one portion its top edge, this may deform sufficiently to allow the engagement part to be inserted but then function to retain the engagement part. Alternatively, if in profile, each of the recess and the engagement part have a suitable shape, e.g. polygonal e.g. a three-dimensional rhomboid type shape so that the base elements 42 and 50 are wider than the top of the recesses 38 a, 38 b, 38 c, then the mid-sole and/or the inner-sole engagement parts may be sufficiently deformed to allow insertion of the inner-sole engagement parts 44 a,b,c, into the corresponding recesses 38 a,38 b, 38 c of mid-sole 30 such that they are not able to be disengaged afterwards during normal use of the footwear.

FIG. 3B shows a further retaining feature 56 in the base of the mid-sole 30, which may be provided to allow an additional retaining element to be provided within recess 38 a. Not shown in the example in FIG. 3B is a corresponding additional engagement part 58 extending from engagement part 44 a, however, as would be apparent to one of ordinary skill in the art, such an engagement part could comprise an additional type of glue-less or adhesive free fixation mechanism could be used such as are well known in the art, for example, a screw, dowel, pin, nail, staple or the like, either directly into the mid-sole or with a “wall-plug” type fixing means being used as well. Well-known mechanisms such as a nut and bolt may also be used, for example, with a nut being held fixedly within a recess 38 of the mid-sole 30 for example, so as to engage with a corresponding bolt inserted into and protruding from a base 50 of an engagement part 44 of the mid-sole 30, or, for example, a cam-lock could be used. The cam in the case of the latter example of additional fixation means could be inserted within a recess in one or more or all of the inner sole engaging portions, and these could then engage with a screw head inserted laterally in the mid-sole to engage in a manner well known to those of ordinary skill in the other. Other possible fixing mechanism may include, for example, a snap-fastener mechanism providing a sort of press-stud type of engagement mechanism.

As each of the inner sole engagement parts 44 a,b,c, protrudes through shoe sock 16, the engagement of the inner sole 46 with the mid-sole 30 also fixes the shoe-sock 16 in position between the inner-sole 46 and mid-sole 30. This enables glue-less or adhesion-free construction of at least part of the item of footwear 10 as the engagement of the inner sole 46 and mid-sole 30 holds the shoe sock in place and enables the mid-sole to be additionally fixed to the shoe-sock, for example, by stitching, stapling or by using other suitable technique.

FIG. 3C is a black-and-white photograph providing a view of the base of the outer sole of an item of footwear 10 according to an example of an embodiment of the disclosed technology which has the mid-sole 30 partially cut away to remove the medial half. The medial side of the item of footwear now shows the bases of the protruding engagement parts 44 a,b,c of the inner sole.

FIG. 3D is a black-and-white photograph providing a rear side-view of the heel region 20 a of the item of footwear 10 according to an example of an embodiment of the disclosed technology which shows the side-wall 48 of the rear engagement part 44 a of the inner sole (not visible as within shoe sock 16).

FIGS. 4A to 4C are a black-and-white photographs enlarging the forefoot, mid-foot, and heel regions of the image shown in FIG. 3B.

In FIG. 4A the forefoot of an item of footwear according to an embodiment of the disclosed technology is shown. In FIG. 4A, inner sole engagement part 44 c protrudes through an aperture in shoe sock 16 to engage with recess 38 c in mid-sole 30. The forefoot end side wall 48 of the engagement part 44 c forms an angle 54 c with the base 50 c of the engagement part and the rear foot end foot sidewall 48 of the engagement part 44 c forms an angle 52 with the base 50 c of the engagement part 44 c. In the embodiment shown in FIG. 4A, the recess 38 c is retained within the midsole 30 and does not protrude to the base of the midsole or otherwise to any exterior part of the item of footwear 10. The size and/or shape of the recess 38 c forms a retaining element which engages with the protruding engagement part 44 c of the inner sole 46 so as to grip the shoe sock 16 and hold this in place. Also shown in FIG. 4A is a forefoot end side wall 48 of the inner sole engagement portion 44 b which makes an angle 54 b with the base of the engagement part 44 b.

In FIG. 4B the mid-foot 20 b of an item of footwear 10 according to an embodiment of the disclosed technology is shown. In FIG. 4B, inner sole engagement part 44 b protrudes through an aperture in shoe sock 16 to engage with recess 38 b in mid-sole 30. The forefoot end side wall 48 of the engagement part 44 b forms an angle 54 b with the base 50 b of the engagement part and the rear foot end foot sidewall 48 of the engagement part 44 b forms an angle 52 b with the base 50 b of the engagement part 44 b. In the embodiment shown in FIG. 4B, the recess 38 b is retained within the midsole 30 and does not protrude to the base 32 of the midsole or any other exterior part of the item of footwear 10. The size and/or shape of the recess 38 b forms a retaining element which engages with the protruding corresponding engagement part 44 b of the inner sole 46 so as to grip the shoe sock 16 and hold this in place. Also shown in FIG. 4B is the forefoot end side wall 48 of the inner sole 16 retaining portion 44 c which makes an angle 52 c with the base of the engagement part 44 c.

In FIG. 4C the rear foot or heal region 20 b of an item of footwear 10 according to an embodiment of the disclosed technology is shown. In FIG. 4C, inner sole engagement part 44 a protrudes through an aperture in shoe sock 16 to engage with recess 38 a in mid-sole 30. The forefoot end side wall 48 a of the engagement part 44 a forms an angle 54 a with the base 50 a of the engagement part and the rear foot end foot sidewall 48 a of the engagement part 44 a forms an angle 52 a with the base 50 a of the engagement part 44 a. In the embodiment shown in FIG. 4C, the recess 38 a is retained within the midsole 30 and does not protrude to the base 32 of the midsole or any other exterior part of the item of footwear 10. The size and/or shape of the recess 38 a forms a retaining element which engages with the protruding corresponding engagement part 44 a of the inner sole 46 so as to grip the shoe sock 16 and hold this in place. Also shown in FIG. 4C is the forefoot end side wall 48 b of the inner sole 16 retaining portion 44 b which makes an angle 52 b with the base of the engagement part 44 b.

The inner sole engagement part 44 a and reciprocating recess 38 b as shown in FIG. 4C may engage solely by virtue of their three-dimensional shape, but they may also be provided with additional means of engagement, such as are described in more detail herein below, one example of such an additional means of engagement is the slot- or groove like recess 56 shown in the base of the recess 38 in midsole 30, such as could engage with an additional corresponding element extending from the inner sole engagement part 44 a (not shown in FIG. 3C). Such an additional engagement part 60 could be provided by a dowel or the like protruding or being formed as an extrusion from the base 50 a of the engagement part 44 a. Alternatively, a recess could be provided in engagement part 44 a into which a dowel or other suitable fixing means such as a screw or pin etc., could be provided.

FIGS. 5A to 5D are black and white photographs showing a different views of a model of a base of an item of footwear according to an example of an embodiment of the disclosed technology.

In FIG. 5A an example of a midsole 30 according to an example of an embodiment of the disclosed technology is shown as a unitary body in which the three recesses 38 a,b,c have being integrally formed (for example, by molding the entire midsole 30 from a suitable material/materials and/or machine tooling a blank or any other well-known manufacturing method include 3D printing). Similarly, the inner sole 46 is shown as a single or unitary body formed with three protruding male engagement parts 44 a,44 b,44 c, which may be machine tooled with the inner sole from a blank and/or molded and/or otherwise extruded from the underside of the foot-bed of the inner sole using a suitable manufacturing method, such as, for example, 3D printing. In other embodiments however, the midsole 30 may be formed from a blank and the design elements such as the side wall 34 and fixation region 36 may be formed after the main body of the mid-sole has been formed.

FIG. 5B is an enlargement of the image of FIG. 5A showing in more detail the form of the inner sole 46 from which extend the three sole engagement parts 44 a, 44 b, 44 c.

FIG. 5C shows in more detail another view an example of a midsole 30 according to an example of an embodiment of the which comprises a side-wall 34 and fixation rim 36 the three engagement parts or recesses 38 a, 38 b, 38 c. Each recess 38 a,b,c, has the shape of a rhombus in side profile and a rectangle when viewed from above. The shape of each recess 38 a,b,c may not be the same and they may differ in some embodiments and even with the same shape their dimensions will change in order to be accommodated completely within mid-sole 30. Each recess accordingly has four walls 40 surrounding a base 42.

In FIG. 5C, the base 42 a of recess 38 a in the heel or rear end 20 a of the midsole 30 is deeper than those of the mid- and fore-foot recesses 38 b and 38 c and includes an additional retaining element comprising a further recess 56, which can be seen more clearly in the image shown in FIG. 5D which is an enlargement of the image shown in FIG. 5C.

In the embodiment of the rear-end recess 38 a of the mid-sole 30 shown in FIG. 5C. the base 42 a has an additional cut out section 56 which allows further engagement with inner sole 46.

FIGS. 6A to 6D are schematic cross-sectional views of different examples of engagement mechanisms for the inner and outer sole portions according to some embodiments of the disclosed technology. FIGS. 6A to 6B also show as large arrows an example of a direction in which a force applied to the inner surface of the inner sole 46 causes engagement with the mid-sole 30 (those of ordinary skill in the art will appreciate that a force in the opposite direction applied to the outer surface of the mid-sole 30 may have the equivalent effect, as would applying forces in both directions).

In the embodiment of the inner and mid-foot engagement mechanism shown in FIG. 6A, inner sole 46 has an integral engagement part 44 which protrudes through shoe-sock 16 to engage with mid-sole 30. In construction and use, the flexing of the item of footwear 10 means that it can be sufficient to provide a “wedge-like” engagement mechanism which has an acute (less than 90 degrees) fore-foot end angle θ and an obtuse (greater than 90 degrees) rear-foot end angle φ with the top of the mid-sole 30 which result in the side-walls 48 of the retaining wedge enabling the inner sole wedge to be slotted or slipped into place by pushing the inner sole 46 in a direction along from the rear-foot end of the mid-sole to the fore-foot end until it clicks into place. Whilst this may be sufficient to retain the shoe sock 16 in place during construction of the item of footwear when this is attached, for example, by stitching or stapling, to the mid-sole 30, this may not be an optimal design for all gaits when the item of footwear is being worn and in use.

FIG. 6B shows another example of an engagement part 44 protruding from inner sole 46 through shoe sock 16 to engage with a corresponding recess 38 with which the engagement part closely conforms in shape. In this example, the fore-foot end angle θ and a rear-foot end angle φ are both acute angles (i.e. both are less than 90 degrees, for example, they may be 85, 80 or 75 or else, for example, 60, 45, or 30 degrees etc.). However, ideally the angles are selected so that they are close enough to 90 degrees to allow the protruding inner sole engagement part to be forcibly inserted into the corresponding recess 38 of the midsole 30 yet not so close to 90 degrees that there is not sufficient engagement to hold the inner sole and mid-sole together when the footwear is being constructed and/or in use.

FIG. 6C shows yet another example of an engagement part 44 protruding from inner sole 46 through shoe sock 16 to engage with a corresponding recess 38 with which the engagement part closely conforms in shape. In this example, the fore-foot end angle θ is acute and the rear-foot end angle φ is obtuse but the same additional engagement part 56 could be provided when are both acute angles as shown in FIG. 6B. The additional engagement part shown in FIG. 6C comprises a nodule or dowel like extension in the base of engagement part 44 which is housed within cavity 56 in the mid sole 30, however, it will be apparent to anyone of ordinary skill in the art that a number of other engagement mechanisms may be formed integrally with the inner sole 46 or provided within the inner sole 46, for example, in the form of a dowel, pin, screen or as FIG. 6D shows, a nut and bolt like mechanism. In FIG. 6, the base of the mid-sole 30 includes a recess 56 providing an additional engagement mechanism which is configured to accommodate a nut 62 in the base 42 of the recess 38. In FIG. 6D, a bolt 60 is shown extending through the inner sole engagement part 44 to additionally engage with the bolt 62 within recessed base 42 of the recess 38 in midsole 30.

Other embodiments of the invention may use other forms of engagement mechanisms and combinations of integrally formed (e.g. molded) engagement mechanisms with additional engagement mechanisms.

For example, in some embodiments the inner sole 46 may be formed integrally with a protruding hollow element having an inner aperture which forms an additional secondary engagement mechanism may be provided, such as a bolt or screw or a snap-fastener type of engagement portion (for example a male snap-fastener portion). In this example embodiment, the mid-sole 30 comprises a reciprocating engagement portion, for example, a female snap-fastener. Further additional fixing means may also be provided in the form of a secondary fastening mechanism, for example, the male engagement part 44 may be provided with one or more apertures in the base 42 and shaped to allow a further secondary engagement portion 60 in the form of a screw, bolt, or secondary male or female snap-fastener type element to pass through and engage with a corresponding secondary reciprocating snap-fastening engagement element formed in the female engagement part recess of the mid-sole 30 so as to provide an additional form of fixation mechanism to fixedly engage the inner sole 46 with the midsole 30.

In such a manner an inner sole may, for example, be provided with at least one integrally formed male engagement portions 44 a,b,c, each engagement part or portion configured to function as one or more nested male snap-fastener mechanisms and the mid-sole may be integrally formed with one or more female recess portions 38 a,b,c, each providing one or more reciprocating nested female snap-fastener mechanisms arranged to receive and engage with the male snap-fastener mechanisms in one embodiment of the disclosed technology.

Those of ordinary skill in the art will appreciate that in some embodiments it may be possible instead and/or in addition to forming apertures in the shoe-sock through which the protruding male engagement part(s) 44 extend to instead deform the shoe-sock sufficiently to allow the contours of the inner sole 46 engagement parts 44 to engage with the reciprocating engagement parts in the mid-sole 30.

Some embodiments of the invention may invert the male and female engagement elements so that the female is housed within inner sole 46 and the male within mid-sole 30.

The side profile of the secondary male or female engagement portions may be tapered when in position within the inner sole so as to conform to the inner surface of the inner sole 46, so that in a side view along the axis of the footwear sole, from either the medial side of the foot or the distal lateral side of the foot the top profile of a secondary engagement portion may take the form of a wedge.

Whilst the examples of recesses and engagement parts shown in the accompanying drawings are “wedge-like” a number of different shapes and configures may be used providing they are configured to allow the inner sole 46 to engage with the mid-sole 30, as a “snap-type” fastener type of design, for example, when viewed from above looking down on the shoe or in a direction where the base of the shoe faces the viewer, the mid-sole retaining elements comprising the retaining recesses and the correspondingly shaped inner sole engagement parts may instead of being rectangular instead comprise a square, a circle, an oval, a hexagon or other polygon, or a star type shape etc. etc. In some embodiments, the inner sole may be constructed so as to contain the recesses or “female” engagement part, with the male “protruding” engagement part being provided in the mid-sole.

Whilst the term “mid-sole” has been used here, in some embodiments of the invention, this may form the outer-sole of the item of footwear 10.

Any range or device value given herein may be extended or altered without losing the effect sought, as will be apparent to the skilled person.

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

Any reference to ‘an’ item refers to one or more of those items. The term ‘comprising’ is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and an apparatus may contain additional blocks or elements and a method may contain additional operations or elements. Furthermore, the blocks, elements and operations are themselves not impliedly closed.

The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. The arrows between boxes in the figures show one example sequence of method steps but are not intended to exclude other sequences or the performance of multiple steps in parallel. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought. Where elements of the figures are shown connected by arrows, it will be appreciated that these arrows show just one example flow of communications (including data and control messages) between elements. The flow between elements may be in either direction or in both directions.

It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. 

1. A footwear sole comprising: an first sole portion including at least one protruding male engagement part; a second sole portion including at least one recessed female engagement part having a shape which closely conforms to that of a corresponding male portion, whereby when a force is applied to the first sole portion in the direction of the second sole portion, the corresponding male engagement part is fixedly retained by the female engagement part.
 2. A footwear sole as claimed in claim 1, wherein the first sole portion comprises an inner sole positioned within a shoe-sock and the at least one corresponding protruding male engagement part passes through an aperture in said shoe-sock to engage with said recessed female engagement part.
 3. A footwear sole as claimed in claim 2, wherein the footwear sole is used in the construction of an item of footwear and retains the position of the shoe-sock relative to the second sole portion whilst the shoe-sock is fixed to the second sole portion using non-adhesive based retaining technique.
 4. A footwear sole as claimed in claim 3, wherein the non-adhesive base retaining technique comprises stitching the shoe-sock to the second sole portion.
 5. A footwear sole as claimed in claim 1, wherein the second sole portion comprises a mid-sole of an item of footwear.
 6. A footwear sole as claimed in claim 1, further comprising: at least one additional engagement part located in at least one of said at least one protruding male engagement part; and at least one reciprocating additional engagement part located in at least one of said at least one recessed female engagement part.
 7. A footwear sole as claimed in claim 6, wherein at least one of the at least one additional engagement parts protrudes from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.
 8. A footwear sole as claimed in claim 6, wherein at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.
 9. A footwear sole as claimed in claim 7, wherein the protrusion comprises an additional component part that passes through at least part of the protruding male engagement part.
 10. A footwear sole as claimed in claim 7, wherein the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.
 11. A method of constructing an item of footwear, the method comprising: forming a first sole portion having at least one protruding male engagement part; forming a second sole portion having at least one recessed female engagement part; positioning the first sole portion within a shoe-sock, such that said at least one protruding male engagement part extends through the foot-base of the shoe-sock; positioning a second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part; and forcing the first sole portion against the second sole portion such that the male engagement and female engagement parts engage fixedly with each other to grip the shoe sock in a substantially fixed position.
 12. A method as claimed in claim 11, wherein the shoe-sock is further secured to at least one of the second sole using an adhesive free technique.
 13. A method as claimed in claim 12, wherein the adhesive free technique comprises stitching.
 14. A method as claimed in claim 11, wherein the second sole portion comprises a mid-sole of an item of footwear, and the method further comprises covering at least part of the mid-sole with an outer sole.
 15. A method as claimed in claim 11, further comprising: forming at least one additional engagement part in at least one of said at least one protruding male engagement part; forming at least one reciprocating additional engagement part in at least one of said at least one recessed female engagement part, wherein when the positioning of the second sole portion to align the at least one recessed female engagement part with a corresponding protruding male engagement part aligns the additional engagement part with the reciprocating engagement part.
 16. A method as claimed in claim 15, wherein forcing the first sole portion against the second sole portion such that the protruding male engagement and recessed female engagement parts to engage fixedly with each other to retain the shoe sock in position further causes the additional engagement part and the reciprocating additional engagement part to engage with each other.
 17. A method as claimed in claim 15, wherein forcing the first sole portion against the second sole portion such that the protruding male engagement and recessed female engagement parts engage fixedly with each other to retain the shoe sock in position further causes the additional engagement parts and the additional reciprocating engagement part to be suitably located for engaging using a different mechanism.
 18. A method as claimed in claim 15, wherein at least one of the at least one additional engagement parts protrudes from the base of the male engagement part and at least one of the at least one reciprocating additional engagement parts comprises an additional recess in the base of the female recessed engagement part.
 19. A method as claimed in claim 15, wherein at least one of the additional engagement parts protrudes from the base of a recessed female engagement part and at least one of the at least one second additional engagement parts comprises a recess in the base of the male recessed engagement part.
 20. A method as claimed in claim 17, wherein the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess or cam-type locking mechanism in a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.
 21. A footwear sole as claimed in claim 8, wherein the protrusion comprises an additional component part that passes through at least part of the protruding male engagement part.
 22. A footwear sole as claimed in 21, wherein the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.
 23. A footwear sole as claimed in 8, wherein the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism.
 24. A footwear sole as claimed in 9, wherein the at least one protruding additional element comprises one or more of the following: a dowel and the reciprocal element comprises a recess; a screw and the reciprocal element comprises a recess; a bolt and the reciprocal element comprises a nut in a recess; a male part of a snap-fastener type mechanism and the reciprocal element comprises a female part of a snap-fastener mechanism. 